parallels: Remove unused JSON fetch of "OS"

Commit id ac1c77f0 removed the "os" field in "parallelsDomObj" that
commit id aa296e6c had added and the data is not used by the function.

src/parallels/parallels_driver.c

@@ -814,9 +814,6 @@ parallelsLoadDomain(parallelsConnPtr privconn, virJSONValuePtr jobj)
     if (!(pdom->home = strdup(tmp)))
         goto no_memory;
 
-    if (!(tmp = virJSONValueObjectGetString(jobj, "OS")))
-        goto cleanup;
-
     if (!(state = virJSONValueObjectGetString(jobj, "State"))) {
         parallelsParseError();
         goto cleanup;